Problem: $\dfrac{7}{8} + \dfrac{4}{5} = {?}$
Explanation: $ = {\dfrac{7 \times 5}{8 \times 5}} + {\dfrac{4 \times 8}{5 \times 8}} $ $ = {\dfrac{35}{40}} + {\dfrac{32}{40}} $ $ = \dfrac{{35} + {32}}{40} $ $ = \dfrac{67}{40}$